Tunnel lining



Sept. 5, 1939. T. w. MoRAN 2,172,030

' TUNNEL LINING Filed June 1, 1957- Patented Sept. 5, 1939 UNITED STATES TUNNEL LINING Thomas Whitley Moran, Liverpool, England Application June 1, 1937,

In Great Britain June 6,

13 Claims.

The present invention relates to facings or secondary linings, for underground or under water works such as tunnels, tube railway stations, subways, mines, cellars, magazines and the like.

The terms facing and lining employed herein are used to indicate an inner sheathing of an underground tunnel or the like, this sheathing being provided in this invention either for the sake or appearance and/or to prevent disgure- 10 ment or damage to the finished intrados or to persons or property in the tunnel by dampness or moisture percolating through the main structure, or for other purposes, for example, to prevent damage to the mainstructure of railway tunnels due to the deleterious action of the smoke blast of locomotives. 'Ihe facings or linings referred to in the present specification are not relied upon to contribute strength to the main structure, which may be formed for instance of concrete, 20 brickwork, masonry, or cast-iron, or of bare rock hewn from the solid strata.

In this specification tunnels with bui-lt up structural lining will 'be referred to as a particular and one of the most important examples of underground works to which the present invention may be applied and in order to avoid repetition of the above list of underground works to which the invention may be applied, the terms tunnel, tunnels and the like or underground works such as tunnels will be used in the -following specification and claims Wherever the context permits as representing such list of underground works. The tunnel itself including its structural lining will be described as the tunnel or as ythe 35 main structure, the facing or secondary lining forming the present invention as the lining, the surface of the lining nearest to the centre of the tunnel as the intrados of the lining, and the vsurface of the lining adjacent to the main struc- 0 ture as the eXtrados of the lining, and these terms will be employed whether the lining -is curved or of any other shape.

The term gunite is used herein to mean a mixtureof cernentitious material and inert aggregate andwater applied as a spray or jet with a machine operating on the known principle of the cement-gun pneumatic placing machine.

As a rule the cementitious material would be Portland cement and the inert aggregate would be sand.

The chief feature of the present invention consists in the provision, in underground works such as tunnels, of an interior lining of the reinforced gunite spaced from the inner surface of the tunnel for providing'afdrainage cavity between the Serial No. 145,894 1936 lining and said inner surface, and drainage openings communicating with the cavity for permitting drainage of moisture from between the tunnel and the lining.v The reinforcement, is preferably of steel wires or rods arranged as a rec- 5 tangular mesh or grid.

An important feature of the invention is that the lining can be made as a self-supporting structure independent for its support upon hangers which might corrode away in course oi time although hangers or other connections to the main structure may be used in the erection of the lining for supporting the same until the gunitehas set.

A still further important featureof the invention consists in a method of constructing a reinforced gunite lining in a tunnel consisting in erecting a. backing of sheet material, spaced inwardly from the main tunnel structure to provide a drainage cavity therebetween, this backing being for the purpose of receiving the layer of gunite and for preventing the gunite material from entering the cavity to be formed between the lining and the main structure; next, erecting steel reinforcement for the lining and. spacing it from the backing and lastly, projecting the gunite on to the backing in one or more layers. The connections between the reinforcement and the backing should preferably be of non-corrodible material.

The backing may, in many applications of the invention, be spaced from the main structure by means of spacing strips which are'erected first, the backing being then erected and secured to the spacing strips.

Apart from the positive drainage which is afforded around the intrados of the main tunnel structure and the consequent improbability of any damage occurring to the lining or to users of the tunnel due to dampness or moisture percola- 40 tion, the invention affords a further important advantage in the case of tunnels of cast-iron segment structure in that it becomes unnecessary to iill up the segments with concrete or other material in order to receive an inner cement rendering or other facing. Furthermore it will not be 1 necessary to take the same care in caulking the joints between cast-iron segments as is usually necessary and thus a considerable saving in cost may be eiiected. In some cases the caulking may be omitted altogether.

The invention also facilitates the insertion of expansionV and contraction joints in the lining with the object of eliminating unsightly temperature cracks therein.

The spacing pieces to which, when these are used, the backing is attached, may be in the form of strips, laths, ribs, blocks, or posts, and they may be either straight or curved according to the requirements of the individual case. 'Ihey may be formed of concrete, gunite, reinforced bitumen sheeting, timber or other suitable material. If timber is used it may be creosoted or otherwise suitably treated.

If the spacers are designed to receive any permanent load or thrust, they should be made of an indestructible material such as concrete, or of steel totally encased in concrete.

In the case of a cast-iron segment tunnel where the spacers are placed in actual contact with the Iianges of the segments, the side of the spacer adjacent to the flanges may have groovesformed upon it to allow seepage from between the flanges to pass out into the cavity.

The spacers are formed to the shape and thickness of the cavity required. The minimum width of the cavity should be 1/2", but where space is available the cavity is preferably wider. The spacers may be fixed in position in contact with the main structure by means of nails, spikes, wires, rods, hangers or the like formed of galvanised iron, copper, stainless steel, or other corrosion resistant material. If of concrete, asbestos cement or the like they may be in the form of beams, ribs, or posts which are self-supporting tand not necessarily connected to the main strucure.

For example, in a tunnel of arcuate section the spacers might be in the form of timber laths running transversely round the intrados of the main structure. Again, in the case of a castiron segmental tunnel the arrangement might be similar, but the laths may be formed of strips of reinforced bitumen sheeting built up in layers to the required thickness, such laths being attached for example to wedges, driven into the space oetween the joints of the cast-iron segments.

The backing may consist of'aV reinforced biturnen felt or other suitable sheeting. Such backing is fixed to the spacers by nails or spikes which are preferably of corrosion resistant material.

In a modification, corrugated sheeting, for instance of galvanised iron or asbestos cement may be employed to serve the double purpose of spacers and backing. The sheeting is xed in position against the main structure, the outwardly projecting corrugations constituting the spacers and the external recesses or spaces between the corrugations providing the cavity. The reinforced gunite is applied to the intrados of the sheeting in the ordinary way. Longitudinally curved corrugated sheeting may also be employed without spacers to form the backing for an arcuate roof portion of a lining, such Asheeting being supported at either end either from the side walls of the lining or from the main structure.

The steel reinforcement for the lining will preferably consist of round steel rods arranged in grids or mats. A convenient form of reinforcement is a steel fabric composed of rods welded together to form a rectangular mesh measuring for example 6" x 3". Reinforcement of the expanded metal type may also be used. One or more layers of reinforcement may be used.

" Where the thickness ofthe lining does not eX- ceed 2% the reinforcement would normally be disposed in one layer, thatlayer being situated at or near the centre of the lining; that is it would be spaced from the backing Vby about 1 or 1%.

The reinforcement is preferably attached to the spacers for example by means of corrosion resistant wires attached to nails driven through the backing and the reinforcement is spaced from the backing by suitable means such as small precast concrete blocks.

The lining itself consists of a gunite rendering. The gunite mixture may consist for instance of one part of cement to three parts of sand measured by volume in the dry state, but other suitable proportions rnay be used. The gunite should be applied at a pressure of from 30 to 40 lbs. per sq. in. measured in the hopper of the pneumatic placing machine. The thickness of the lining will depend upon the structural design calculations for each individual case, and upon the necessity for providing adequate cover over the steel reinforcement. The absolute minimum thickness that can be used with safety may be regarded at 11/2, but a minimum thickness of 2" is preferable, giving more cover over the reinforcement. No maximum thickness is herein defined, but consideration of economy would normally limit the maximum thickness to 3 or 4". In the actual construction the thickness is built up in one or more layers, the individual layers preferably not exceeding 11/2 in thickness. Each layer should be applied as soon as possible after the previous layer has set, and suitable precautions should be taken to prevent lamination of the lining due to lack of bond between the layers.

The lining may be of various forms in cross section, e.,g. arcuate or arch, inverted U or horseshoe; or'again it might be rectangular.

The drainage is dealt with by providing pipes, chases, slots, orifices or weepholes either in the supports or abutments of the lining or in the lower extremities of the lining itself. For supporting the lining suitable bearings may consist for instance of spaced lugs or brackets or longitudinal beams projecting inwardly from the sides of the main structure, or of upstanding columns or plinths, standing on the base of the main structure adjacent to the sides thereof, such lugs, beams or columns having a bearing surface suitably shaped to receive the lower ends of the lining.

Thus the support or abutments may form continuous ledges or they may consist of a series of non-continuous brackets or columns. If continuous ledges are employed, adequate openings must be provided for drainage and ventilation of the cavity behind the lining. When non-continuous bearers are used, the lower extremities of the lining itself should be structurally designed as a continuous beam spanning the spaces between the bearers. The supports or bearers may be of concrete, reinforced concrete, brickwork, steel or cast iron.

When the supports or bearers are formed of concrete it will usually be ,desirable to connect the lower part'of the lining to the supports by the insertion of steel joint rods to prevent any lateral or longitudinal sliding movement between lining and supports.

When the lining is curved in cross-section it may be formed as a two-.hinged or three-hinged arch, in which case the lower end of the lining and also the supports should be of suitable shape in section and of such construction as to act as hinged joints.

While linings of arcuate or arch prole are one of the most important applications of the in- 75 vention, alternative profiles may be employed. For example, a lining of rectangular shape may be designed as a portal structure; alternatively, the sides of such a lining might rest on supports at their bottom ends, While the tops are held in position between thrust blocks on the one side and the ends of the ceiling portion on the other, the latter being carried by corrosion resistant hangers or hangers totally enclosed in concrete and/or gunite secured to the main structure. Y

Another mode of constructing a lining of rectangular shape would be to support the walls as described immediately above and to support the ceiling portion by means of concrete, steel or timber beams resting either on the main structure or on the walls of the lining itself. If it is not practicable to fix a suitable backing to receive the lining between such beams, the beams might be laid side by side in contact so that the backing would be formed by the beams themselves.

In the case of a rectangular tunnel of nonportal design, provision can be made for relative movement between the vertical walls and ceiling slabs by means of buckled strips of copper or the like.

Again, the ceiling might be formed of a series of jack arches running transversely, the arches being supported on longitudinally spaced transverse beams.

When linings of the above substantially flatroof types are used, the ceiling portion must be slightly inclined so as to allow seepage water to run off to the sides or ends.

It will be appreciated that it is not necessary that the lining should be of similar prei-lle to the main structure, For example, an arched lining might be constructed in a rectangular tunnel and vice versa.

Another case is that of a. tunnel in which, the lining is only to be applied to strips on the sides independent of each other, the ceiling or crown being left unlined, or lined in some other way. These strips may themselves be straight or curved to follow the shape of the tunnel. The bottoms of the strips may be supported as previously described, while the tops may be held in position by rag bolts totally enclosed, or by brackets of reinforced concrete or gunite formed for that purpose, or by other suitable means. The walls of an unroofed approach, ramp, or stairway leading for example to a tunnel can be lined in a similar manner.

If desired, provision can be made for the incorporation of soundprooiing material, which might consist for example of insulating sheeting or strapping behind the extrados of the lining.

The interior surface of the gunite may be left as it comes from the discharge nozzle of the gun or may be treated in some other way according to the requirements of the individual case.

In many forms of tunnels and the like underground structures there is provision for drainage underneath the roadway or floor so that the surface of the iioor is dry. In some cases however, no special provision exists, or water may be percolating up through the existing floor from the surrounding ground as well as through the walls and/or roof of the structure. In such cases, in addition to the lining of the walls, or walls and roof, it may be necessary to construct a new iioor raised above the existing floor thus leaving a cavity for drainage. Such raised oor might be constructed on a similar principle to the lining for walls, etc. as previously described, for example, by laying down 'corrugated Vsheeting upon the existing oor, placing reinforcement, and applying the gunite as already described. The downwardly projecting corrugations would form the bearers or supports for the floor, and the recesses between them would form the cavity. A suitable Varrangement would be that shown in Figure `9, but inverted.

Alternatively, the raised floor might be constructed of reinforced concrete bearers and slabs cast in situ, or again of precast reinforced concrete slabs resting upon concrete bearers and bedded in cement mortar. When this type of floor construction is used in combination with the cavity lining, the drainage from the cavity of the lining may be allowed to drain into the cavity below the floor. Suitable means must be provided for draining away and/or pumping out any water that might collect below the raised floor.

The invention is more particularly described with reference to the accompanying diagrammatic drawing in which:

Figure 1 is a cross sectional view showing the application of a cavity lining of the present invention to a tunnel formed of cast iron segments.

Figure 2 is a fragmentary longitudinal sectional view taken on the line 2-2 of Figure 1 but drawn to a larger scale.

Figure 3 is a longitudinal sectional View of a thrust collar for use in connection with the lining of a sloping cast iron segment tunnel.

Figure 4 is a fragmentary cross sectional View illustrating a junction between a flat ceiling and a part circumferenial lining in a tunnel of the type shown in Figure 1.

Figure 5 is a longitudinal sectional View of a further form of tunnel and lining illustrating the mode of constucting the lining.

Figure 6 illustrates the application of the invention to a subway.

Figures '7 and 8 are fragmentary cross and longitudinal sections showing a further form of construction.

Figure 9 is a fragmentary longitudinal sectional view showing an alternative form of mode of constructing a cavity lining.

For sake of clearness, the drawing is not drawn to scale and the parts are shown somewhat out of proportion and considerably thicker than would be the case in actual practice.

The mode of construction the linings according to the present invention can be best described with reference to Figure 5 which shows the progress of the construction from left to right. The first step in the construction is to erect spacer strips I0 at suitable intervals along the tunnel. In a tunnel having a ceiling of arcuate form the strips I0 extend around the ceiling in the transverse direction. The backing Il which may be formed, for instance, of roong felt is then secured to the spacer strips and the reinforcement l2, shown as rectangular steel mesh, is then secured in position on the inside of the backing and spaced inwardly therefrom by means of small distance pieces not shown in Figure 5, but indicated by the reference numeral I3 on Figure 2. The reinforcement is preferably supported from nails which engage through the backing into the spacer strips I0. Preferably the distance pieces I3 are arranged to abut against the spacer strips f' i. e. it is not advisable to arrange the distance pieces I3 midway between two spacer strips so as to abut solely against the backing. After the .reinforcement has been erected the gunite is projected on to the backing.

A weephole I4 is provided in the lining usually between each pair of spacer strips I0 to allow drainage of moisture from the cavity I5 between the lining and the tunnel proper. In the arrangement shown in Figure 5 the tunnel itself is approximately of circular form and on each side of the tunnel longitudinal abutment I 6 are supported by pilasters I'I, such abutments and pilasters being formed for example of concrete or gunite.

Figure 1 is a cross-sectional view of a tunnel formed of cast-iron anged segments 29. The spacer strips 2l drawn to larger scales in Figure 2 are arranged along the transverse flanges of the segments 29. The spacer strips 2l may be secured by nails 22 to suitable insertions 23, for instance of wood, inserted between the anges of the segments. The backing 24 is then secured to the spacer strips 2l by nails 25. The reinforcement 28 is then erected and is spaced away from the backing by means of the distance pieces I3 which may consist of pre-cast concrete blocks. The reinforcement is tied to the spacer strips by means of wire loops 29 engaging under the heads of the nails 25.

Figure 2 illustrates the construction of an expansion joint in the lining. The lining is shown as discontinuous longitudinaly at the point 21 and the transverse groove so formed by the discontinuity is sealed by a buckled copper strip 28 which extends transversely of the tunnel on the inside of one of the spacer strips 2l and is secured on the front of the backing by nails 25. The ends of the reinforcement are tied to the copper strip 28 by wire loops 29. The abutments 30 (Figure l) for the lining are provided with drainage slots 3l and usually one drainage slot 3l is provided in each segment.

Joint rods 32 extend out of the abutments and into the lining. In the construction of the lining the abutments are formed rst 'with joint rods 32 extending outwardly to be covered later by the material of the lining when this is applied.

For the purpose of illustration the form of the lining on the left-hand side of Figure 1 is shown as diferent from that on the right-hand side of Figure 1. On the left-hand side of Figure l the lining is thickened outwardly adjacent the abutment as at 33. In the actual construction of the lining this can be done by cutting away the spacer strip 2i and suitably bending the backing outwardly.

In the form of construction shown at the rightnand side of Figure 1 the lining is thickened at a point 34 by cutting away the spacer strip 2| or by applying it in discontinuous pieces. The backing 24 is bent outwardly at the point 34 toprovide an auxiliary abutment integral with the lining.

Figure 3 illustrates a thrust collar suitable for use in the application of the invention to a sloping tunnel formed of cast-iron segments. The segments are referenced 36, the backing 37, the reinforcement 38, the lining 39 and the spacer strips dii. The thrust collar coincides with an eX- pansion joint 4I similar to that shown in Figure 2. Prior to the application of the lining one transverse row of the segments 36 is partially lled with concrete 42 to leave a notch or step 43 and reinforcing rods 44 in the concrete V42 project outwardly through the step to be tied to the reinforcement of the lining. The backing 31 is discontinuous at the step so that when the material of the lining is applied the step is lled withA gunite which is integral with the gunite of the lining so that the thrust of the lining is applied to the step.

Figure 4 shows one mode of erecting a lining in conjunction with a flat ceiling in a cast iron segment tunnel. The fiat concrete ceiling 46 is formed prior to the construction of the lining 41 and abuts on the longitudinal flanges 48 of the cast iron segments. Ragbolts 49 project inwardly from the margin of the ceiling to form a tie between the ceiling and the upper end of the lining.

The backing 50 is cui; away locally at the point 5I to enable the material of the lining to be projected directly on to the margin of the ceiling in this region and totally to enclose the ragbolt 49. A bitumen joint strip 52 is interposed between the ceiling and the upper end of the lining.

Figure 6 illustrates a self-supporting cavity lining for a subway. The ceiling part 65 of the lining is formed continuously with the wall part 66. The cavity and spacer strips are indicated at El, the backing at 68 and the reinforcement at 69. The wall part 66 of the lining sits on an abutment 'i9 from which reinforcing rods 'Il project into the lining. Longitudinally spaced thrust pieces 'I2 are provided on each side of the tunnel adjacent to the upper end of the wall portions 65. The thrust pieces are preferably formed of concrete.

The constructions so far described refer to separate spacer strips to which the backing is applied. In many cases however the spacer strips may be combined with the backing by the use of Fluted, grooved or corrugated material I4 as shown in Figure 9, in which the tunnel proper is indicated at "i5, the lining at 'i3 and the reinforcement at TI. The corrugations 'I8 serve as spacer strips.

The corrugated material may consist of sheet asbestos-cement or sheet metal.

In the arrangement shown in Figures 7 and 8 the side walls |94 of the lining join the arch I 06 which abuts against longitudinally spaced concrete thrust pieces |95 and the backing for the ceiling is formed of corrugated sheet material I B9 which is supported on the thrust pieces |95 and from which the reinforcement |97 is suspended by suitable wire loops H38. In this case the backing for the ceiling is self supporting across the space, and spacers are not required above it either for support or otherwise.

I declare that what I claim is:

l. In underground works such as tunnels, an interior lining of reinforced gunite spaced from tht inner surface of the tunnel for providing a drainage cavity between the lining and said inner surface, and drainage openings communicating with the cavity for permitting drainage of' moisture from` between the tunnel and the lining.

2. In underground works such as tunnels, a main tunnel structure, a backing secured to the main tunnel structure and spaced therefrom to provide a drainage cavity, an interior lining of gunite projected onto said backing, and drainage openings communicating with the cavity for permitting draining of moisture from between the main tunnel structure and the backing.

3. In underground works such as tunnels, a main tunnel structure. an interior lining of gunite spaced from the inner surface of said main tunnel structure, a backing onto which said lining of gunite is projected, said backing being spaced from the interior surface of said main tunnel structure to provide a drainage cavity, and reinforcing means for said interior lining spaced from said backing and imbedded in said lining.

Y 4. In underground works such as tunnels thev main tunnel structure, an interior lining of reinforced gunite spaced from the inner surface of said main tunnel structure, whereby to provide a drainage cavity between the lining and the main tunnel structure, abutments supporting said interior lining, and means providing drainage openings for permitting the drainage of moisture from between the main tunnel structure and the lining.

5. In underground works such as tunnels, as claimed in claim 4, the provision of drainage openings in the abutments.

6. In underground works such as tunnels, as claimed in claim 4, the provision of abutments extending transversely between the main tunnel structure and the lining and drainage openings in the lower portion of the lining.

'7. In underground works such as tunnels, as claimed in claim 3, the provision of backing formed of corrugated sheeting, having the outwardly projecting corrugations serving as spacers whereby to provide drainage cavities between the remaining portions of the sheeting and the main tunnel structure.

8. In underground works such as tunnels, a non-horizontal main tunnel structure, an interior lining of reinforced gunite spaced from the inner surface of said main tunnel structure for providing a drainage cavity between the lining and the main tunnel structure, drainage openings communicating with the cavity for permitting the draining of moisture from between the main tunnel structure and the lining, and means interposed between the lining and the main tunnel structure for absorbing longitudinal thrust.

9. In underground works such as tunnels, a main tunnel structure, an interior lining of reinforced gunite spaced from the inner surface of said main tunnel structure for providing a drainage cavity between the lining and the main tunnel structure, drainage openings communieating with the cavity for permitting the draining of moisture from between the main tunnel structure and the lining, and transversely running expansion and contraction joints disposed at intervals in said lining.

10. In underground works such as tunnels, as claimed in claim 9, the provision of expansion and contraction joints consisting of buckled strips of relatively non-corrosive and relatively pliable material such as copper disposed adjacent the outer surface of the lining, and reinforcing means for the lining to which the expansion and contraction joints are tied.

11. In underground works such as tunnels, a main tunnel structure including cast iron segments having inwardly extending flanges, spacing strips secured to said anges, a backing secured to said spacing strips and thereby spaced from the flanges of said segments to provide drainage cavities between the segments and the backing, and an interior lining of reinforced gunite projected on to said backing, and drainage openings communicating with said cavities for permitting drainage of moisture from between the main tunnel structure and the lining.

12. The method of constructing a lining for underground works such as tunnels, which consists in erecting a backing spaced inwardly from the inner surface of the main tunnel to provide a cavity therebetween, placing a reinforcement for the lining spaced inwardly from the backing, and projecting gunite onto the backing to a depth greater than the spacing of the reinforcement from the backing.

13. The method of constructing a lining for underground works such as tunnels, which consists in securing spacing elements across the interior surface of the main tunnel, erecting a backing spaced inwardly from the inner surface of the main tunnel to provide a cavity therebetween, securing the backing to the spacing elements, placing a reinforcement for the lining spaced inwardly from the backing, and projecting gunite onto the backing to a depth greater than the spacing of the reinforcement from the backing.

THOMAS WHI'ILEY MORAN. 

